* [http://www.economist.com/theworldin/international/displayStory.cfm?story_id=3372495&d=2005 The Economist] (quality of life survey)
* [https://www.cia.gov/library/publications/the-world-factbook/appendix/appendix-b.html The World Factbook] (developed countries)
* [https://web.archive.org/web/20080327210253/http://unstats.un.org/unsd/cdb/cdb_dict_xrxx.asp?def_code=491 United Nations Statistics Division] (definition)<!-- archived -->
* [https://web.archive.org/web/20050511011954/http://unstats.un.org/unsd/mi/developed_new.htm List of countries, United Nations Statistics Division] (developed regions)<!-- archived -->
* [http://www.worldbank.org/data/countryclass/classgroups.htm#High_income World Bank] (high-income economies)